Liquid contact circuit closer



LIQUID CONTACT CIRCUIT CLOSER Filed Sept. 13, 14941- Inventor z` Walter' Ger-isch,

His Attest-neng.

' Patented Dec. l, 1,942

Walter H. Gerisch, North Bergen, N. J., as signor to General Electric Company,V a corporation of New York Application September L13, 1941, Serial No. 410,661

(Cl. 20G- 152) 7 Claims.

' The present invention relates to circuit closers ofthe type having an envelope which contains a small quantity of mercury arranged to complete and interrupt a circuit between the terminals of the circuit closer.

It is a primary object of' the invention to provide improved circuit-closers vof the type speciiied above and more particularly to increase to the safe current carryingcapacity of such circuit closers. In this connection, I have discovered that high temperature arcs heretofore incident to the 'operation of mercury-containing circuit closers and the attendant destructive effects of such arcs can be minimized by the introduction into the circuit closer of a conditioning medium which contains hydrogen and oxygen, both in substantial proportions.

For an explanation of the invention and for a consideration of what I believe to be novel, attention is directed to the accompanying description and the claims appended thereto.

In the accompanying drawing;

Fig. 1 is a sectional elevation of a liquid contact circuit closer (switch) embodying my invention; and

Fig. 2 is a sectional elevation of another type of liquid contact circuit closer also embodying the invention. A

The circuit closer illustrated in Fig. 1 of the drawing has an envelope I containing a limited if* quantity of mercury 2. The major portion of the envelope comprisesvopposed straight-drawn cup-shaped metal terminals 3 juxtaposed to form an enclosed space between them. Between the terminals is a diaphragm or barrier 4 of insulating material having an opening 5 therein through which the mercury flows in order to complete a circuit between the terminals 3, 3. When the said circuit closer-is in the position illustrated, the circuit between the terminals is complete. The members 3, 3 are hermetically joined by means of a thin ring 6 of glass or other thermoplastic ,material sealed directly thereto in such is completed by the joining of mercury flowing into the opening 5 from each end thereof.

Heretofore, in the commercial production of cir-v cuit closers of this type, the switch has been first the operation of the switch in opening and closing a circuit therethrough.

I have now discovered that in the manufacture y of these switches if the step of evacuating the air therefrom is omitted and in addition to the air normally present in the switch there is added thereto hydrogen ranging in pressure from about a few pounds to an atmosphere or even much higher pressures, the arc-suppressing eiect of the gaseous iilling is materially enhanced and the improvement is so great as to double the current which may be interrupted by a given form of switch without excessive erosion of the barrier. Such hydrogen may be introduced into the circuit closer during the manufacturing process through an opening 1, provided in the metal member 3. This opening 'I is thereafter sealed, preferably by fusion-welding a closure member 8 therein, for example, in accordance with the procedure described and claimed in John H.

Payne Patent 2,141,932, issued December 27, 1938.

of air and hydrogen in barrier type switches are also obtainable in switches of other types, such,

for example, as the pellet or cartridge type of` mercury switch shown at 9 in Fig. 2. This comprises metal terminals I0 and II of iron or nickel plated iron or chrome-iron spaced apart by a tubular insulating sleeve I2 of fibre or glass pressfitted to the metal terminals with a thin layer of adhesive resin I3 interposed between the metal and the insulating sleeve to insure a gas-tight seal at the respective end junctures thereof. A globule of mercury I4 provided within the switch serves to connect and disconnect the terminals Ill and II as the switch is moved into its open andclosed positions.

While a complete explanation of the advantageous results obtained by the use of a mixture of hydrogen and air as a switch lling is not yet available,v there is enough evidence at hand to show that these results are attributable at least in part to the effect of the oxygen content cf the air in conditioning the contacty surfaces of the parts within the interior of the switch. For example, itis found that when a mercury switch which contains admixed hydrogen and air is oppears on the surface of the mercury. This nlm Vhas the apparent eifect of increasing the ability of the mercury to perform its circuit-closing and circuit-interrupting functions. Moreover, it appears that the metal surfaces within the switch are affected in such a way, presumably by slight oxidation, as to decrease the likelihood of a destructive arc being established to these surfaces during the operation of the switch. In this connection it has been repeatedly observed that a switch which has been filled with air and hydrogenproduces, during the closing operation, an arc which is very much less intense than that obtained with hydrogen alone. The improvement in this respect and the attendant decrease in the destructive effects obtained during the arcing period are so great as to more than double the circuit-interrupting capacity of a switch of given size.

A significant' phenomenon which has been observed during the operation of a switch filled with air in combination with hydrogen consists in the variation of the heating effect which occurs during the initial period of use. During the first few operations on high load the switch tends to become quite warm, indicating an intense arcing condition. However, after operation has been 1 continued for a short time this eiect disappears 'and the switch runs at a lower temperature, aV

condition which appears to endure indefinitely as long as the switch is used in a normal way. If the switch is materially disturbed, as by taking it from its socket and shaking the switch structure,

renewed operation will result in temporary heating, this condition again disappearing, however, with a further continuance of use.

It is believed that the foregoing observations erated several times an observable oxide lm apmercurous oxides or suitable oxides of nitrogen (e. g. nitrous oxide).

While the invention has been described by reference to two types of switch, it is obviously not limited thereto and I aim in the appended claims to cover all such equivalent applications as come within the true spirit and scope of the foregoing disclosure.

What I claimas new .and desire to secure by Letters Patent of the United States is:

1. A mercury-containing switch comprising metallic electrodes cooperating with the mercury to complete a circuit through the switch and conditioned by a gaseous filling within the switch comprising atmospheric air qualified by the addition thereto of free hydrogen at a pressure of y from one to several atmospheres.

2. A mercury-containing switch comprising metallic electrodes cooperating with the mercury to complete a circuit through the switch and conditioned by inclusion within the switch of a gaseous liing which comprises free oxygen at relaat substantially the pressure at which it exists in show that a certain amount of time is required for the formation of the oxide film referred to above as being produced on the surface of the mercury. Once this lm is produced, however, it appears to exist indefinitely and to exert a helpful influence on the operation of the switch.

Insteadof producing the desired lling merely by adding hydrogen to the normal air content of the switch, switches may alternatively be charged from a tank containingk a mixture of air and hydrogen. As a still further alternative, the hydrogen normally used for switch fillings may be qualied by an addition of pure oxygen (i. e. instead of air). In either of these last two cases the switches can be iiushed a few times by the gaseous mixture and then sealed off at the pressure found desirable.

Still further, oxygen may be introduced into the switch interior in other than a gaseous form.

atmospheric air and free hydrogen at relatively much higher pressure.

4. The method of preparing a mercury switch which includes assembling the switch parts under such conditions as to leave the switch filled with air, introducing hydrogen into the switchin additionto the air, and thereafter sealing the switch.

5. The method of preparing a mercury switch which includes assembling the switch parts under such conditions as to permit the retention within the switch enclosure of air at atmospheric pressure, and thereafter introducing hydrogen at a pressure of at least several pounds per square inch.

`6. A mercury switch comprising metallic elements'adapted to serve concurrentlyas wall parts for the switch and as contact members cooperating with the mercury for establishing a circuit through the switch, said switch containing a gaseous-filling at a pressure above atmospheric pressure and 'comprising free hydrogen and free oxygen, both gases being present in substantial amounts.

7. A mercury switch comprising metallic elements adapted to serve concurrently as wall parts for the switch` and as contact members cooperating with the mercury for establishing a circuit through the switch, said switch being conditioned by a gaseous lling at a pressure above atmospheric pressure comprising free hydrogen and free oxygen, the hydrogen preponderating over the oxygen in said filling.

WALTER, H. GERISCH. 

